Fluid-operated pump with singleacting direct-connected booster pump



June 30, 1953 c. J. coBERLY FLUID OPERATED PUMP WITH SINGLEFACTINGDIRECT-CONNECTED BOOSTER PUMP 3 Sheets-Sheet l Filed Jan. 22, 1949 June30, 1953 c. J. coBERLY l 2,643,612

' FLUID OPERATED PUMP vWITH SINGLEACTING DIRECT-commun BoosTER PUMP FldJan. 22, 1949 3 Sheets-Sheet 2 HHRH, Fosa/Ni HAR/ws @Y w m C. J. COBERLYFLUID OPERATED P DIRECT-CONNEC 2,643,612 UMP WITH SINGLE-ACTING TEDBOOSTER PUMP June 3 0, 1953 5 Sheets-Sheet 3 Filed Jan. 22, 1949,Pstentedf- June 3o, 1953 FLU'ID-OPERATED PUMP WITH SINGLE- ACTINGDIRECT-CONNECTED BOOSTER PUMP Clarence J. Coberly, Los Angeles, Calif.,assignor, by mesne assignments, to Dresser Equipment Company, OhioCleveland, Ohio, a corporation oi` Application January 22, 1949, SerialNo. 72,108

, l My invention relates to fluid-operated pumps for wells, and moreparticularly, to a fluidoperated pumping device comprising afluidoperated. main pump having an auxiliary or booster pump associatedtherewith for boosting the pressure of the well fluid delivered Ato theinlet of the main pump.

Reference is hereby made to my co-pending application Serial No. 45,048,filed August 19, 1948; Serial No. 46,776, filed August 30, 1948; andSerial No. 77,588, filed February 21, 1949.

Fluid-operated pumps are commonly used in the oil industry for pumpingoil from wells, such a pump comprising, in general, a coupled motor andpump combination set in the Well at the level from which oil is to bepumped. In such a combination, the motor comprises a motor piston whichis actuated by alternatively admitting an operating fluid, such as cleancrude oil, under relatively high pressure into opposite ends of a motorcylinder in which the motor piston is disposed so as to reciprocate themotor piston. The reciprocatory motion of the motor piston iscommunicated to a pump piston in the pump section of the combination sothat the pump piston pumps oil from the well. Y

The fluid being pumped from a well may contain, in addition to oil,various other fluids such as water and natural gas, the gas beingpresent in solution or in suspension in the oil in varying quantitiesdepending upon the pressure and temperature conditions prevailing in thewell. Also, if the well is being pumped beyond its capacity to produce,air may be present in the fluid being pumped. If the oil is saturated orsupersaturated with natural gas at the conditions of pressure andtemperature prevailing at the level at which the pump is set, a largeportion of the gas may be released during the suction stroke of the pumppiston to form a gas pocket in the pump cylinder. Also, of course, inmany wells the well fluid is merely a, froth composed largely of gaswith a relatively small volume of oil. In either case, or if air isdrawn into the pump cylinder, a pocket of gas or air in the pumpcylinder results. Such pockets result in a material reduc tion in thepumping load until such time as the pump piston compresses the gas orair present and strikes solid well fluid in the cylinder.

Such fluid-operated pumps are frequently set at relatively great depthsand, consequently,'a large volume of `operating fluid under relativelyhigh pressure is confined in the supply tubing between the pump in theWell and the apparatus on the surface which delivers the operating fluid1o claims. (c1. 10s-5) to the pump. Due tothe appreciablecompressibility of this large volume of operating fluid, and due to theexpansion of the supply tubing under the relatively high pressure atwhich the operating iiuid is maintained, a large amount of energy isstored under normal operating condi" tions. If, because of the presenceof gas or air in the pump cylinder, the load on the pump pistondecreases, a sudden increase in the rate of iiow of operating uid to thepump occurs, thereby accelerating the motor and pump pistons. The speedultimately attained may be excessive and the pump may race for a portionof a stroke or'for a number of strokes, which is normally detrimental tovarious Vcomponents `of the pump. Various expediente for preventingdamage to the pump mechanism under such conditions have been employed.For example, flow regulators disposed in the supply line for theoperating fluid have been employed to maintain the rate of delivery ofoperating iiuid to the motor section of the pump below a value whichmight be harmful to the pumping equipment. While such ow governors arepractical under most conditions of operation, they have somedisadvantages in that they increase thev cost of the pumping equipmentand render the equipment rather complicated. Also, there is some lag intheir operation since they respond only after the condition requiringcompensation has already developed.

Also, the presence of gas or air in the pump cylinder has a detrimentaleffect on the eiciency 0f such a fluid-operated pump. For example, if,in a given installation, thirty percent of the pump cylinder of thehuid-operated pump contains free gas or air, the efliciency of the pump,i. e., the percentage of the volume of the pump cylinder which containssolid well fluid, will be only seventy percent. In other words, undersuch conditions, the fluid-operated pump will pump well iiuid from thewell at only seventy percent of capacity.

In view of the foregoing considerations, it is a primary object of thepresent invention to provide, in combination with aV conventionalfluid-operated pump, an auxiliary or booster pump which is adapted todraw well fluid from the well and to deliver it to the inlet of theuidoperated pump atr an increased pressure such that the major portionof the gas or air in the well fluid will not flash out to form a pocketin the pump cylinder of the main pump. I accomplish this by providing a`booster pump which will maintain the pressure of the well uid pass- 3ing into the pump cylinder of the main pump at a value equal to or abovethe pressure prevailing in the well at the inlet of the pumping device.A further object of the invention is to provide a booster pump which`will compress :any free gas or air entrained in the well fluid to asubstantial extent before it is delivered to the inlet of the main pump.

It will be apparent that employing pump in combination with afluideoperated main pump in the foregoing manner will obviate, or atleast minimize, the diiiiculties hereinbefore disa .booster pistonhaving pressure relief valve means for bypassing well fluid from thehigh pressure end of the booster pump cylinder to the low pressure endthereof in the event that the pressure ofthe welllfluid 'delivered totheaccumulator and/or to the inletV of themain pump tends to exceed apredetermined value.

' `-.Another object of the invention is to provide vsuch4a.pumping,.device wherein the rod means cussed. In otherrwords,thewemployment .oriabooster pump will tend to obviate-A racing ci'A themain pump and to increase the pumping-let;- ciency thereof. As anexample, let it be as- .connecting the .various pistons is hydraulicallybalanced withrespect to well fluid pressure.

The foregoing objects and advantages of the :present-invention. togetherwith various other i objects and advantages thereof which will besumedthat the pumping efficiencyy ofuthemain pump is only seventy percentwhen the pressure at the inlet thereof is approximately equal to*Yatmospheric pressure. With the present invention, V.if Athe particular.booster pump.i utilized .is

adapted to. increasezthe pressurezoff thef-wellzluid delivered tothe:inlet.of; theamainpumpftothree hundred pounds perxsquareY inch, .thefreegas` or air which otherwise .would occupyfthirty percent.

of thevolume of the-pump cylinderl oithe. main pump willbecompressedtooccupy only approximately 1.4 percent 'of the volume ofthe pumpr cylinder, thereby increasingithe eiciency of the main pump toapproximately -98.6percent under .l

such conditions.

Another object of the present'invention is to provide such a pumpingdevice,;i. e=,- such a fluid--` operated main pump 4and booster pump,combination, in which they booster-pump is directly connected tothemainxpumpsoas to beoperable thereby.r More specically,;it isfan obectvto `provide a fluid-operated pumping device wherein the boosterpumpv'includes4 a booster pump piston directlyconnected4 by rod means tooneof the pistons of the main pump,rpr eferably the pump piston.thereof.V

-A furtherobject of the invention is gto pro-` cumulator ofY annularcross` section, .which 4is adapted to. receive and sulfzstantialhgvenclose .the-

main pump.

Another object istofprovide-a pumpingtdevicef wherein the tubularaccumulatorghaslmeans con.-Y

nected theretorforproviding -agpump-rseatior; the

main pump. f

Another object-istoprovide a pumping devicewherein the main pump .isremovable iromg'the tubular accumulator and-wherein. the booster pumppiston is removable from the boosterpump cylinderlconcomitantly.withremoval of themain pump from the accumulator;

Another-.object is to providefafpumping-'device wherein thezaccumulatorandthe` boosterV pump cylinder. are connectedrbyv-a tubular-fittingwhich provides-.thepump seat-for-the mainfpump and .throughwhich the.booster pump piston may be withdrawn fromtheboosterpump cylinder, therod means connecting therbooster pump pistonY with oneof the pistonsoithe; main pump extending through` such tubular fitting.

Another Objectis to provide agboosterv pump come apparent, maybeattained through the utilization of the exemplary embodiment of the in--ventionwhich .is-.illustrated in the accompanying drawings and which isdescribed in detail hereina-iter;v Referring to the drawings:

Fig. l is a utility view on a reduced scale showingr aiiuid-operatedpumping vdevice which embodiesithe inventionasinstalled ina well Vliiglla` isa longitudinal sectional View taken alongthearrowed.line l'a-lc .of 1 of the drawing;

Eig-.12A is; alongitudinal sectional view of the upper end of apreferredi'booster pump of the invention and is taken. along vthe`broken line 2-2 oiFig. l ofithe drawings;

Fig.y Suis a downward continuation of Fig. 2`

and is taken alongfthebrokenline 3-'3 of Fig. l; fEig.lis'atransverse'sectional view taken along therbroken line 4--41offEig'. 1;/

Figs.Y 5 and .6 are transverse sectional viewstaken.alongthegbroken.lines5?-5 and 6*(5, respectively, of' Fig-..2 randY vFigir isa transversesectionalzview taken along the'broken. line 1-:1cf;'1ig..3.of` the drawings.

Referring. particularly .to;Fig. 1 of the draw- .:ings, I. show-.anoilwell` lined. with a casing IG havingperforations I l; whichregisterwith` an oil producing formation t2 andxthrough which oil and. otherfluids mayflowv into the interior of the casing, the-fluids entering thecasing being Acollectively..referredto hereinafter as the well fluid.Extending downwardly: into the casing It) is a .production tubing lf3`which. is adapted to convey well' fluid tothe surface of the ground, andextending downwardly into the production r ytubingin the particularvconstruction illustrated is a power'tubing'l'd havingia fluid-operatedmain or primary pump l5 connected to the lower end thereof. Connected totheilower.- endv of the production tubing' lf3. is a tubular fitting lewhich,

r ,a asbest. shownv in Fig'. 2: of the-drawings, provides a tapered pumpseat H. orxthe main pump l5. Secured relative to the. lower end of themain pumpy l5 in axial-alignment therewith is an auxiliary Yorboosterpumpl' which is adapted to pump well fluid from the casing l0 tothe inlet of themain pump at a pressure higher than that obtaining atthe intake. of 'the booster pump, as will be discussed inY more detailhereinafter.

The fluid-operated main pump t5 may be of any conventional type, Asuchas that shown in my Patent No. 2,081,220', issued May 25, 1937, which isadapted to pump welliiuid from the casing lil4 upwardly through theproduction tubing i3 to the surface. As shown best in Fig. la o thedrawings, the huid-operated main pump i5 is provided'withamotor=cylinder 2l having a motor piston 22 therein, and'. is providedwith a pump cylinder 23 having a pump piston 24 therein,4 the motor; andpump pistons respectively being provided with. longitudinal passagesA25- and 26 therethrough. Connected to the upper end of the motor piston22 and communicating with the passage therethrough is an upper tubularrod 21 which extends into a balance chamber 28 at the upper end of themain pump I5. Connecting the motor pump pistons 22 and 24 andcommunicating with the passages 25 and 26 therethrough is anintermediate tubular rod 23, and connected to the lower end of the pumppiston is a lower tubular rod 35 for directly connecting the main pumpI5 to the booster pump I8 as will be discussed in more detailhereinafter, the lower tubular rod extending through the tubular fittingl5. l f

Briey, the fluid-operated main pump I5 operates as follows: Operatinguid, such as clean crude oil, under relatively high pressure isalternatively admitted into the ends of the motor cylinder 2! toreciprocate the motor piston 22 therein, such reciprocatory motion ofthe motor piston being communicated to the pump piston 24 by theintermediate tubular` rod 29. rihe pump piston 24 discharges fluidintothe production tubing I3, which conveys the fluid upwardlyto thesurface.

Considering the pumping devicein more detail, the main pump i5terminates at its lower end in a tting 33 having a tapered head 34 whichis adapted to seat on the pump seat I1: provided by the tubular ttingI5, and having a stem 35 which is insertable into the tubular fittingI6. The ritting 331s provided with a bore 36 therethrough for the lowertubular rod 3i), the latter being encircled by packing 31. As best shownin Figs. 2, 5 and 6 of the drawings, the iitting 33 is provided with aplurality of longitudinal passages 38 therethrough which act as inletports for the main pump i5, and isprovided with a plurality oflongitudinal passages li which terminate in radial passages 4Icommunicating with an annular space i2 between the production tubing I3and the main pump i5 so as to deliver fluid pumped by the main pump tothe production tubing, the passages 40 and 4I providing outlet ports forthe main pump.

Connected to the lower end of the tubular fitting i5 in axial alignmentwith the motor and pump cylinders 2| and 23 of the main pump i5 is apump cylinder 45 of the booster pump I8, the booster pump cylinder #i5being provided with an intake port i5 which communicates with the wellcasing i5 to admit well iiuid into the booster pump cylinder. Outflowfrom the booster pump cylinder through the intake port 45 is preventedby a check valve 41.

Reciprocabie in the booster pump cylinder 45 is a booster pump piston 55which, as best shown in Fig. 3 of the drawings, includes a tubular uppersection 5i, a tubular intermediate section 52, and a tubular lowersection 53 in the particular construction illustrated. The lower tubularrod 3@ is threaded into a stem 5d on the upper section 5I of the boosterpump piston so as to communicate reciprocatory motion of the motor andpump pistons 22 and 24 of the main pump I5 to the booster pump piston,as will be discussed in more detail hereinafter. As will be apparentfrom Fig. 3 of the drawings, the lower end of the lower tubular rod 3@is exposed to well iuid pressure, and such pressure is also communicatedto the balance chamber 25 at the upper end of the main pump i5 throughthe lower tubular rod 35, the passage 26 through the main pump piston25, the intermediate tubular rod 29,

the passage 25 through the motor piston 22, and

y that of the lower end of the lower tubular rod 35 so that the rodassembly is hydraulically balanced with respect to well fluid pressure,which i is a feature of the invention.

' Referring againto Fig. 3 of the drawings, clamped between theintermediate and lower sections 52 and 53 of the booster pump piston 55is a packing cup 51, the latter surrounding a portion of theintermediate piston section 52 in the particular constructionillustrated. Surrounding a portion of the lower piston section 53 isanother packing cup 58 which is clamped between the lower piston sectionand a washer 59, the latter being retained by a flange 6I! on a tube 6Iwhichis threaded into the intermediate piston section ,52.r Extendingthrough the tube 6I and threaded into the upper piston section 5i is atube 62 having a flange 63 at its lower end, a compression spring 64encircling the tube 62 and being seated at its ends against the flangesSii and 63. The lfunction of the spring 64 is to maintaincomplementarily tapered surfaces S5 and 66 on the respective pistonsections 5I `and 52 in uid-tight engagement, unless the pressure in thebooster'pump cylinder 45 above the piston 50 exceeds a predeterminedvalue.v If this occurs, the spring 64 is compressed to permit separationof the tapered surfaces 65 and 6E to permit fluid to flow from the upperVend of the booster pump cylinder 45 into the lower end thereof by wayof radial openings 61 in the tube 62. Thus, the booster pump piston 53provides a pressure relief valve means for by-passing fluid from thehigh pressure side of the booster pump piston 50 to the low pressureside thereof, i. e., from the upper end of the booster pump cylinder 45'to the lower end thereof, in the event that the pressure on the highpressure side of the booster pump piston exceeds a value determined bythe spring 64,2which is a feature of the invention.

The upper section 5I of the booster pump piston 50 is provided withlongitudinal passagesJi which communicate with an annular groove12therein, the latter communicating with the interior of the tubular uppersection 5I. Thus, during downward movement of the booster pump piston50, well fluid from therebeneath may flow upwardly therethrough by wayof the tube 52, the ,tubular upper section 5I, the annular groove 12 inthe tubular upper section, and the longitudinal passages 1I therein.Reverse flow through `the booster pump piston 50 "during upward movementthereof is prevented by a check valve means 13 comprising a plurality ofball valves 14 which are adapted to close the longitudinal passages 1I,the upper piston section 5I being provided with inserts 15 which serveas seats for the ball valves. The ball valves 14 are held by a retainer16 which is urged downwardly to retain the ball valves in engagementwith their seats by a compression spring 11, the latter being seatedagainst a nut 13 threaded on the stem 54 on the upper piston section5I.As will be apparent, the spring 11'prevents opening of the check valvemeans 13 during the upward, or working stroke of the booster pump piston55, and permits opening thereof during the downward stroke of thebooster pump piston. Thus, the booster pump i8 is of the single-actingtype, fluid being discharged from the boosterpump cylinder 45 during theupward stroke of the booster pump 50. v f

Z Fludpdisplacedg-by',thefboosterpump piston ,-50 duringi itsyworkingVVstroke is :discharged from the upperA endv of the booster; pump cylinder45' through discharge ports. 8l which` communicate Y with theinletyports: 3.8 .for Vthe main pump l through an annular space 82. The.annular space'ris defined by asleeve 3-3 pressedon a1 reduced-diameter.portionof the fitting 33, andthe discharge ports 3l are formedin a valveseat member-8.4whichisseated againstthe lower end of the sleeve 83, thevalve seat. member being retained byma nut 85V threaded on a sleeve 86which .encircles the tubular,l lower rod and is threaded into the lowerend` ofthe bore 36v through'A the. fitting v311i; l

A` check valve means; 901 similari to the `check valve means "I3permits-.upward now throughthe discharge portsal ,duringfthe upward or.work-- ing :stroke .of thel booster .pump piston andpreventsidownwardflow. therethrough during the downward stroke: of ltherbOosterA pump piston, the check; valve means 9i) comprising. aplurality of ballvalvesll Yadaptedlto seat on inserts 92v carried; bythe i-'valvef seat memberi 84: and-encircling the discharge ports. 8ltherethrough. The ball valves 9i fare retainedby a retainer 93. and areadapted to be heldseatedagainst theinserts 92 by acompressionspring .94whichfis disposed be'- tween theretainer 93- and the lower end of thefitting 33.

Inorderf to maintain theuid delivered to the inlet ports 3.87ct themainpump; l5 under pressure; during the-downward"V stroke of the boosterpump piston` SLI provide anV accumulator 166 which `communicates 'withthe inlet ports 33 throughradial passages? lili .inthe tubular fittingI6, anannular groovev H12 yin this tting, and radial passages H33 infthetting. 33. The accumulatcr. lis tubular, i. e., of annular crosssection, and: comprises an annular space |05 between the productiontubing |43 and a tube or. shell IOB which 'encircles the lower end ofthe production tubing and which is connected at-` its lower. end to and.extends upwardly from the'tubular tting I6, as best. shown in Fig. 2 ofthe drawings. The, shell |06 Ymay extend upwardly from the` tubularfitting l5 a distance such thattheV accumulator Ireceives a column offluid of sulhcient height to maintain theY desired pressure inthe-inletports 38 of the main pump l5 hydrostatically, in which case theaccumulator may be; open. at itsupper end. However, in order toavoidthenecessity of employingan accumulator l'of excessive length,particularly when a high pressurey is to be maintained in the inletports 38, I prefer to close the accumulator lui! at its-upper end, as bymeansof aseal'ingiring {D'I- (Figs. l and 4)V interposedbetween theshell [66 .and the production tubing The operationoi my pumping devicewill be apparentfromthe foregoing'so that only a general descriptionthereof is thought to be necessary. During the downward stroke of themotor and pump pistons 22 and 24 of the main pump i5, the boosterpumppiston 50 is moved downwardly initscylinder 45, fluid from the lower endof the booster pump. cylinder iiowing through the booster pump vpistoninto the upper end thereof by wayV of the check valve means 13. Duringthedownward stroke Vof the booster pump piston, downward` iiow ,throughthe discharge portsrl isaprevented by thefcheck valve means 90. As themotorpiston22 moves upwardly, it moves the booster pump piston 50Vupwardly by means ofthe .intervening connection so that: thebooster-"pump piston displaces fluid from the upper.endofitheboosterpump cylinder past the check valve means vSi), nowthrough the booster pump pistonduring its workingstroke being preventedvby thecheckvalve means 73. The fluid discharged-by the booster pump I3in this manner is deliveredeither tothe main pump i5, or to theaccumulator Hill.V During the downward, or nonworking stroke of thebooster pump piston, fluid flows into theinlet ports 38 of the main pumpfrom the accumulator |06, thelatter maintaining the desired pressure. inthe inlet ports during the nonworking stroke of the booster pumppiston.. Thus, the accumulator lili] provides a continuous flow of.iluid at substantially constantpressure to the-inlet `ports 33 of themain pump l5.

Thus, the auxiliary or booster pump I8 delivers well uidto theinletports 38 of the uid operating mainpump l5 at an elevated pressureto minimize the formation of gas or air pockets inthe pumpcylinder-23:of the main pump, whereby 4to increase the-eiiiciency of the main pumpand to minimize the possibility of damage to the components thereofwhich may result from the formation oigasor air pockets in the pumpcylinder `3 as previously discussed. The booster pump. I8 preferablydelivers a relatively large volume of well fluid to the main pump at arelatively low pressure, the effective cross-sectional area of theboosterrpump piston 50 being substantially larger than that of the motoriston 22 to accomplish this. In practice, the ratioof booster pumppiston area to motor piston area may be 4- to l, for example. rihus, themajor portion ofthe work necessary toV pump weligfluid tothe-surfacesperformed by the main pump i5, the function of the booster pump I8being to deliver the Welluidto the main pump at a pressure suicient onlyto prevent excessive formation ofv gas pockets inthe pump cylinder 2-3kof themain. pump, which pressure preferably exceeds thev pressureobtaining at the intake port 46 of the booster pump.

Intheeventthat'the pressure developed in the accumulator lill)V risesabove the value determined by the,l spring 64 for any reason, thepressure relief valvemeans incorporated in the pump piston 50 willoperate to by-pass iiuid from the high Vpressure side of the boosterpump piston to the low pressure side thereof, as hereinbefore discussed.

Inorder tofacilitate removal of the main and booster pumps I5 and I8 forservicing or repair, the ,internal diameter of the tubular fitting i6 ispreferably at least equal to the diameter of thebocster pumpV piston 50so that the latter may be; removed from its cylinder through the tubularfitting V1 6 concomitantly with removal of the main pump from thetubular accumulator N39. Thus, with the exception of the booster pumpcylinder 45 and the check valve 4l controlling fiow through the intakeport 46, all components of the pumping device which are subject to wearmay be pulledin a single operation without any necessityofpulling theproduction tubing i3 and the-accumulator l E26, whichis a feature of theinvention.

Although I have disclosed an exemplary embodiment of theinventionforpurposes of illustration, it will be understood that various changes,modications and., substitutions may be incorporated the'. speciiicembodiment disclosed Without .necessarily departing from the .-facfracial. In a fluid-operated pumping device, fthe;

combination of: a tubularv accumulator adapted to be positioned in awell; means providing a pump seat secured to said'accumulator; auidoperated main pump of thereciprocating type adapted to seat on saidpump seat, said main pump being provided with an inlet port; a singlefacting, auxiliary pump of the reciprocating type secured relative tosaid main pump in axial alignment therewith, said auxiliary pump beingprovided with an intake port adapted to communicate with the well andbeing provided with a discharge port communicating with said inletvport; means providing iiuid communication between said accumulator andsaid discharge and inlet ports; and means mechanically connecting saidauxiliary pump to said main pump for operating said auxiliary pump so asto pump Well fluid from the Well into said inlet port and saidaccumulator at a pressure higher than that in said intake port.

2. A duid-operated pumping device as set forth in claim 1 wherein saidpump seat is located adjacent the lower end of said accumulator andwherein said accumulator,substantially encloses said main pump.

3. A fluid-operated pumping device as set forth in claim 1 wherein saidauxiliary pump comprises a cylinder secured to said accumulator andhaving a pump piston therein, and wherein said main pump comprisesconnected motor and pump pistons, said means mechanically connectingsaid `auxiliary pump to said main pump comprising rod means forconnecting said pump piston of said auxiliary pump to said pistons oi'said main pump.

4. In a huid-operated pumping device, the combination of: a tubularaccumulator adapted to be positioned in a well; a tubular iittingconnected to the lower end of said accumulator and provided with a pumpseat; a fluid-operated main pump of the reciprocating type adapted to bepositioned in said accumulator and to seat on said pump seat, said mainpump including axially aligned and connected motor and pump pistons andbeing provided with an inlet port, asingleacting, auxiliary pumpprovided with an intake port adapted to communicate withthe well and adischarge port adapted to communicate with said accumulator and withsaid inlet port, saidy auxiliary pump including a pump cylinder securedto the lower end of said tubular fitting and including a pump piston insaid pump cylinder; passage means for connecting said discharge port,

Vsaid accumulator and said inlet port;'and rod means extending throughsaid tubular fitting and directly connecting said pump piston of saidauxiliary pump to said pistons of said main pump for operating saidauxiliary pump so as to pump weil fluid from the well into said inletport and said accumulator at a pressure higher than that in said intakeport.

5. In a fluid-operated pumping device, the combination of: a tubularfitting adapted to be positioned generally vertically in a well andprovided with a pump seat; a fluid-operated main pump of thereciprocating type adapted to seat on said pump seat and includingaxially aligned, connected motor and pump pistons, said main pump beingprovided with an inlet port for well iuid and `being adapted to pumpwell fluid from e 10 thewell to the surface; an auxiliary pump of thereciprocating type including a pumpy cylinder con- 'fnected to the lowerend of said tubular tting and axially aligned with said motor and pumppistons of said main pump, kand including a pump piston reciprocableinsaid pump cylinder, said auxiliary pump having anintake port adapted to-communicate with the well andhaving a dis- Y chargeport; passage meansindependent of and outof fluid communication with said intake port forconnecting said discharge port to said inlet port; and rod meansVextending through said tubular iitting and -connecting said pump pistonof 'said auxiliary pumpV to said motor and pump pistons of said mainpump for operating said auxiliary pump so as to pump well fluid from thewell into said inlet port at a pressure higher than that in said intakeport.

6. A fluid-operated pumping device as set forth in claim 5 wherein theinternal diameter of said tubular fitting is at least equal to thediameter of said pump piston of said auxiliary pump to permit Withdrawalof said piston of said auxiliary pump through said tubular fitting.

7. In a huid-operated pumping device, the combination of: afluid-operated main pump having a balance chamber, a motor cylinder, apump cylinder and 4an inlet port communicating with said pump cylinder,said main pump including a tubular motor piston in said motor cylinder,a tubular pump piston in said pump cylinder and a main tubular rod meansconnecting and cornmunicating with the interiors of said motor and pumppistons and having an end extending into said balance chamber; anauxiliary pump of the reciprocating type secured relative to said mainpump and including a pump cylinder having a tubular pump piston therein,said auxiliary pump being provided with an intake port adapted tocommunicate with the well and a discharge port communicating with saidinlet port; and anv auxiliary tubular rod means connecting said pumppiston of said auxiliary pump to said motor and pump pistons of saidmain pump for operating said auxiliary pump so as to pump well fluidfrom the Well into said inlet port at a pressure higher than that insaid intake port, said auxiliary tubular rod means communicating withsaid main tubular rod means and said intake port.

8. In combination with production and power tubings set in a well and apump seat connected to one of said tubings in alignment therewith, afluid-operated pumping device movable downwardly in the well throughsaid one tubing to seat on said pump seat and including: a iiuidoperatedmain pump of the reciprocating type actuable by an operating fluid underpressure in said power tubing to pump well uid into said productiontubing, said main pump having an' inlet port; an auxiliary pump of thereciprocating type provided with an intake port adapted to communicatewith the well to receive well iluid from the well and provided with adischarge port for well iiuid; means for connecting said discharge portin fluid communication with said inlet port so as to deliver well fluiddischarged by said auxiliary pump to said main pump to be pumped therebyinto said production tubing; and means mechanically connecting saidauxiliary pump and said main pump for actuating said auxiliary pump soas to pump well fluid from said intake port into said inlet port at apressure higher than that in said intake port.

V9. A combination according to claim 8, including in addition: a tubularmember connected to

